Process for the production of a continuous filamentary yarn

ABSTRACT

A PROCESS FOR THE PRODUCTION OF A SPUN CONTINUOUS FILAMENT SYNTHETIC YARN HAVING VARIABLE PROPERTIES ALONG ITS LENGTH COMPRISING APPLYING TO THE SPUN, SOLIDIFIED, UNDRAWN YARN A PLASTICISER FOR THE YARN MATERIAL IN AN AMOUNT VARYING ALONG THE LENGTH OF THE YARN TO PRODUCE RELATIVELY PLASTICISED YARN PORTIONS AND RELATIVELY UNPLASTICISED YARN PORTIONS AND THEREAFTER DRAWING THE YARN TO AN EXTENT SUCH THAT VARIABLE PROPERTIES ARE IMPARTED ALONE ITS LENGTH.

United States Patent 3,591,672 PROCESS FOR THE PRODUCTION OF A CONTINUOUS FILAMENTARY YARN Stanley Davies, Goytre, and Haydn Leigh Canton, Cwmbran, England, assignors to Imperial Chemical Industries Limited, London, England No Drawing. Filed Nov. 22, 1967, Ser. No. 684,954 Claims priority, application Great Britain, Dec. 8, 1966, 55,062/ 66 Int. Cl. Dtlld 5/20 U.S. Cl. 264-167 8 tClaims ABSTRACT OF THE DISCLOSURE A process for the production of a spun continuous filament synthetic yarn having variable properties along its length comprising applying to the spun, solidified, undrawn yarn a plasticiser for the yarn material in an amount varying along the length of the yarn to produce relatively plasticised yarn portions and relatively unplasticised yarn portions and thereafter drawing the yarn to an extent such that variable properties are imparted along its length.

The present invention relates to a process for producing continuous filament synthetic yarns having properties varying along the length thereof. It relates particularly but not exclusively to such yarns when made from nylon.

Many methods have been described in the patent literature and elsewhere for the preparation of continuous filament yarns having properties, such as thickness or dyeafiinity, which vary along the length of the yarn and which yarns are used for producing fabrics of novel and pleasing appearance. Such yarns, for convenience, will be hereinafter called variable yarns.

The methods described include pulsating extrusion of the molten polymer at the spinning stage, variable cooling of the melt spun yarn, plucking of the yarn while it is being drawn, drawing in a nonuniform manner and the like.

When such variable yarns are made into fabric and the fabric dyed, the portions with varying properties have different appearances, for instance they exhibit varying degress of lightness and darkness, and when these effects are properly exploited such fabrics can be very pleasing.

According to the present invention there is provided a process for the production of variable yarns as hereinbefore defined wherein a yarn plasticiser is applied to a continuous undrawn yarn made from synthetic polymer in an amount varying along the length thereof and said yarn is subsequently drawn.

The present invention further provides a process for the production of variable yarns as hereinbefore defined wherein a yarn plasticiser is applied to a continuous undrawn yarn made from synthetic polymer in an amount varying along the length thereof in a programmed manner and said yarn is subsequently drawn.

The ease with which undrawn synthetic polymer yarns draw depends to a considerable extent on their temperature and their plasticizer content. For many synthetic polymers, such as nylon, water functions as such a plasticiser. Hence, if the water content of an undrawn yarn varies along the length of the yarn, on subjecting such yarn to a continuous drawing operation those parts containing most water will draw most easily and quickly while those parts containing little or no water will draw less easily and more slowly.

Continuous drawing is usually carried out by feeding the undrawn yarn from a feed roll, across a space known as the drawing zone, and onto a draw roll having a greater peripheral speed than that of the feed roll. If in the drawing zone there are portions of yarn some with a relatively ice high water content and some with a relatively low water content then those with a higher water content will draw easily and quickly, leaving those with a lower water content relatively undrawn. Such relatively undrawn portions will hereinafter be termed nubs.

In this way drawn yarn having variable water content and drawn to varying degrees along its length will be produced. Such yarn when dyed will absorb a dyestulf 1n a varying manner.

It has been found in practice that the pattern of denier variation along the drawn yarn follows substantially the pattern according to which the plasticiser is applied to the spun yarn.

'Of course, the length of the drawing zone has an effect on the variation produced and it must be long enough, for a given yarn drawing speed, for differential drawing to take place to the required degree. By choosing suitable drawing zone lengths subtle secondary effects on the primary variation can be obtained.

Another factor of importance is the natural draw ratio of the spun yarn. In general the higher the natural draw ratio the more pronounced the variation produced in the drawn yarn. The meaning of the term natural draw ratio is well known in the art and may be defined as the ratio of the cross sectional areas before and after a neck formed in the yarn when said yarn is drawn at a mechanical draw ratio at or below said natural draw ratio. For optimum results the yarn should be drawn below the natural draw ratio, preferably at a ratio of around half the natural draw ratio. A high natural draw ratio can be obtained by using a low spinning speed or by the use of suitable nucle ating agents. It is known to draw below the natural draw ratio to obtain variable yarn. With the method of the present invention, the positions where successive necks are formed in the drawing Zone are determined substantially by the positions where the plasticiser is applied.

If the plasticiser used is water, then should the undrawn yarn be allowed to remain in contact with an atmosphere of a fixed relative humidity there will be a tendency for all parts of the yarn to reach the same, equilibrium water content. For this reason the yarn must be drawn as soon as possible after the variable application of water has been performed. Conveniently drawing may follow immediately and continuously after spinning, in a so-called spin-draw process. This precaution is not so necessary, of course, if a non-volatile plasticiser is used. However, even a non-volatile plasticiser may tend to spread along the yarn instead of remaining in patches and so in this case also drawing should be carried out as soon as possible after application of the plasticiser. Such a non-volatile plasticiser could be, for instance a non-volatile hydroxy-compound such as glycerol, and could be applied in admixture in a suitable medium.

Such a mixture may contain plasticiser-fixing agents such as thickeners, high surface tension producing agents, or other agents which will bond physically or chemically with the yarn and the plasticiser in such a way as to restrain this latter from spreading along the yarn.

There are a number of ways in which a variable amount of water or other plasticiser can be applied to spun, undrawn yarn.

A preferred method is to apply varying amounts of spinning finish (an aqueous emulsion of oily ingredients) at the spinning stage instead of endeavouring, as is the usual practice, to apply the finish evenly.

The usual way of applying such finish is to pass the yarn as it is spun continuously over a rotating roll the peripheral surface of which is continuously wetted with the finish by having one part of the roll dipping into a bath of the said finish. The yarn is made to contact an arc of the periphery of the said wetted roll by being guided thereon by guide pins.

By moving such a guide pin in a suitable manner the length of arcuate contact between the yarn and the rotating roll can be varied and such movement of the pin may be of such extent as to remove the yarn from the said roll. In this way the amount of finish applied to the yarn can be varied along the length of the yarn.

By suitably varying the amplitude and rate of movement of said pin the length of contact between yarn and roll can be varied in such a way as to obtain a desired pattern of water content along the yarn.

Clearly, other methods of obtaining a water content which varies along the length of the undrawn yarn will suggest themselves to those skilled in the art. For instance dabbing of absorbent material onto the roll, so removing finish from it in patches, may be performed. The relatively dry patches will of course transfer relative- 1y little finish to the yarn thus producing a length of yarn with a relatively low water content,

If desired spinning finish can be applied uniformly and a plasticiser applied non-uniformly previously or subsequently to such finish application.

Another method is to wind undrawn yarn having a relatively uniform water content to form a package, using varying traverse length. The package is allowed to remain in an atmosphere wherein the equilibrium water content of the yarn is different from its actual water content. The yarn at or near the exposed edges will thus acquire a water content different from that of the rest of the yarn.

The undrawn yarn may be passed, at any stage prior to drawing, through a suitable means for applying a plasticiser such as water, alone or in admixture with other agents, for example dyeing modifiers which alter the rate of dye-absorption or the colour produced by the dyeing process, in an amount varying along the length of the yarn.

Programming of operations suitable for obtaining such variable plasticiser content, such as varying the movement of a guide pin, varying the applicator roll speed, varying ejection of the plasticiser from a jet, varying traverse stroke and the like may be performed using any of the many already Well known means. Using for instance suitable electronic and mechanical equipment programmes of almost any complexity may be devised, such as short repeat patterns, long repeat patterns, pseudo-random patterns and the like.

From the aesthetic point of view the preferred drawn yarn nub parameters are as follows:

Ratio of longest to shortest nub up to 12/1 Maximum nub length: below 20 ins.

Nub spacing: below 100 inches Ratio of longest to shortest nub spacing up to 7/1.

Average nub peak denier: 1.3 to 4 times the denior of the drawn sections.

A particularly preferred yarn has nub parameters as follows:

Nub length: 1 to 20 ins.

Ratio of longest to shortest nub up to 12/1 Nub spacing: 15 to 100 ins.

Ratio of longest to shortest nub spacing up to /1 Average nub peak denier; 1.5 to 3 times the denier of the drawn sections.

A very convenient programming method is to use the signals from a pseudo-random signal generator to control the operation of the plasticiser applicator.

It will readily be appreciated that the present invention is general in nature and may be operated with many types of synthetic polymer yarns, such as polyethylene terephthalate, using suitable plasticisers applied in a varying manner to the yarn before said yarn is drawn.

Furthermore, the effects obtained using the present invention can be combined with other effects, for instance the yarn may be bulked or crimped by known methods, either during the drawing operation or at any other suitable stage in yarn manufacture.

The present invention will now be illustrated, in no way limitatively, by the following examples.

Example 1 (1) A nominally 1040 denier 68 filament yarn was spun and drawn in one continuous operation (spin-draw) under the following conditions:

repeat dis- The finish was applied to the spun yarn using a conventional finish roll technique. An upper cross-pin, guiding the yarn to make arcuate contact with the roll, was made displaceable in such a manner that such displacement caused the length of arcuate contact between the yarn and roll to vary approximately between 0 and inch at an average frequency of about 10 times per second. The displacement of the said pin was controlled according to a pseudo-random programme initiated by a pseudo-random signal generator.

The best nub definitions were obtained at 15 r.p.rn. roll speed (critical to :1 r.p.m.) with resulting oil on drawn yarn of 0.5%.

These conditions gave a yarn with denier variations corresponding to the pseudo random programme, namely:

Nub length approximately 1.6 to 4 ins.

Nub spacing approximately 20 to 50 ins.

Nub peak denier approximately between 1.5 and 3 times the denier of the drawn sections.

Over the whole length of the programme (extending over 1250 ft.) the nub positions corresponded substantially with those predicted by the programme.

The yarn was then down-twisted to 0.6 t.p.i. and incorporated in the weft of a woven fabric. When dyed with a rate sensitive blue dyestuif a pleasing medium blue fabric with dark blue or black streaks in the weft direction resulted.

Example 2 A nomintl 1040/ 68 gear-bulked yarn was produced under the following conditions, in a spin-draw-bulk process, with finish applied as in Example 1.

Polymer: 6.6 nylon with 0.03% TiO Spun denier 2618,

drawn denier 1048 Length of drawing zone=28 ins.

Feed speed 800 f.p.m.Gear speed 1750 rpm.

Wind-up speed=2000 f.p.m.

The yarn was drawn over a hot snubber pin at C. before enter the gear intermeshes. The gears had 20 teeth/ in. and a 27,000 intermesh. Finish roll type: Bauxalite; finish roll speed=11 r.p.m. Finish contained 10% oil, giving an oil on drawn yarn of 0.3%. This yarn, after down-twisting to 0.3 t.p.i., was incorporated in the Warp of a woven fabric with a production bulked nominal 1040/ 68 yarn in the weft. This was dyed with a rate sensitive golden yellow premetalized dyestuff which gave an aesthetically pleasing pale yellow fabric with dark orange streaks in the warp direction, with a pleasant handle, considerably less crisp than that of the fabric of the first example. No signs of periodicity were observed in the fabric.

Example 3 A nominally 1040/68 gear-bulked yarn was produced by a split process.

In this process the yarn was spun-drawn, with programmed finish application, and wound up onto a support, in this case a bobbin. This yarn was then further drawn through gears to give a bulked product as in Example 2. We confirmed that the programme was being transferred to the yarn by means of continuous denier testing apparatus and that the nubs were still present after draw-bulking by means of a Fielden Walker tester.

The following spinning conditions were used:

Polymer: 6.6 nylon with 0.03% TiO R.V.=45. Filament cross section: Trilobal; 68 filaments. Spinning speed=1000 f.p.m.

Wind-up speed=2000 f.p.m.

Length of zone between feed and draw rolls=24 ins. (no snubbing pin). Finish containing oil; finish roll; Bauxalite; speed 11 r.p.m. to yield best nub definition, to give a final oil on yarn of 0.4%

The yarn from this step was gear draw-bulked by the following process:

Draw ratio 1.35 Draw speed 1980 f.p.m.

Yarn drawn over a heated snubbing pin at 160 C. through a 3 gear system with teeth/in. and finally twisted to 0.6 t.p.i. When stretched nearly straight, under low tension the nub parameters were as follows: Spacing approximately 22 to 56 ins.; length approximately 2.4 to 8 ins.; peak denier approximately 2.5 to 3 times the denier to the drawn sections.

The resulting yarn was incorporated in a weft knitted construction and dyed blue with a rate sensitive acid dyestuif. A panel with dark blue patches on a light blue ground resulted.

Example 4 A nominal 1040/68 flat yarn was produced under the following conditions, by the split process, using pseudorandom programmed finish application.

Polymer: 6.6 nylon witht 0.03% TiO R.V.=

Cross section: Trilobal Spinning speed: 1000 f.p.m.

Drawing speed: 2000 f.p.m.

Programme repeat distance=1000 ft. (weight 1 /3 Oz.) Finish: 100% di-ethylene glycol Roll speed: 16 r.p.m.

In this case the peak denier produced was approximately 2 /2 times the means.

The spun yarn was then further drawn to a ratio of 1.35 and twisted to 0.6 t.p.i. This was incorporated into a weft knitted fabric and dyed in the same dyebath as fabric from the yarn of Example 3, in a rate sensitive blue acid dyestulf. The nub parameters were as in Example 3.

The resulting fabric presented a light blue ground with darker blue patches, of lower overall contrast than material produced from the yarn of Example 3, giving a more subtle effect. 4

Example 5 A thick-thin yarn, having dye resist portions along its length, was produced by exactly the same processes as in Example 4 except that to an aqueous finish containing 10% v./v. oil there was added 8% w./v. of Lissotan PR (a trade name). The yarn so produced was weft knitted into panels, as were yarns produced by the process of Example 3. Compared with the latter, considerably greater colour contrast between the nubs and background was obtained when the yarn was dyed in a rate sensitive blue dyestuif. An interesting two tone effect was achieved by dyeing a knitted panel of this yarn in a single dyebath containing a non-rate-sensitive blue acid dyestuff and a similar golden basic dyestuif. This gave a fabric with a golden ground with randomly placed blue areas. Finally a fabric was dyed in a rate sensitive blue dyestuif mixed with an orange basic dyestufi'. A pleasing three colour effect was produced, of an orange ground with randomly placed very dark blue patches with light blue ones interspersed. An effect similar to oxidised metal was produced. The nub parameters were as in Example 3.

Example 6 A nominal 205/34 bulked thick-thin yarn was produced by a split process under the following condition:

Polymer: Nylon 6.6 containing 0.3% TiO R.V. -35

Filament No.=34 I Filament section: Circular Finish containing 10% oil in an aqueous base Finish roll speed to obtain best nub definition=12 r.p.m.

(corresponding oil on yarn 0.5

Finish application programme to give average nub parameters: Length, approx. 5 to 15 ins.; spacing, aprox. 30 to ins.; peak denier, approx. 1.5 to 3 times the denier of the drawn sections Spinning speed=1000 f.p.m.

Wind-up speed=2000 f.p.m.

Length of draw zone=72 ins.--no snubbing pin.

Under these conditions the nubs produced corresponded closely with the imposed programme.

The resulting yarn was further draw-bulked to a draw ratio of 1.25 at a drawing speed of 1295 f.p.m.

It was then incorporated in the weft of a plain woven fabric and dyed in a rate sensitive dyestuif. The resulting material was very aesthetically pleasing, the fiat nature being broken up by long dark blue streaks on a light blue ground. No evidence was noted of periodicity in the pattern.

Example 7 Example 1 was repeated, but this time with a strictly periodic programme. The nub parameters corresponded closely with the programme, namely: spacing approximately 25 ins., length approximately 98 ins. peak denier approximately 2 to 2.5 times the denier of the drawn sections.

Example 8 Yarn was spun and drawn in one continuous operation (spin-draw) under the following conditions:

Polymer-Nylon 6.6 containing 0 .2% CaF and 0.2%

TiO

Filaments68, with trilobal cross-section.

Denier1410 Spinning speed-1000 f.p.m.

Drawing and wind-up speed-2000 f.p.m.

Finish-aqueous emulsion with 10% oil.

Finish roll materialBauxalite Speed-11 r.p.m.

Length of draw zone22 ins.

Snubbing pin-2 ins. diameter and heated to 100 C.

The finish was applied to the spun yarn using a conventional finish roll technique. An upper cross-pin, guiding the yarn to make arcurate contact with the roll, was made displaceable in such a manner that such displacement caused the length of arcuate contact between the yarn and roll to very approximately between 0 and inches at an average frequency of about 10 times per second. The displacement of the said pin was controlled according to a pseudo-random programme initiated by a pseudo-random signal generator.

The best nub definitions were obtained at 11 r.p.m. roll speed (critical to :1 r.p.m.) with resulting oil on drawn yarn of 0.3

These conditions gave a yarn with denier variations corresponding to the pseudo-random programme, namely:

Nub length approximately 22 to 5 6 ins.

Nub spacing approximately 2.4 to 8 ins.

Nub peak denier approximately 3 to 3.5 times the denier of the drawn sections.

We claim:

1. A process for the production of a spun continuous filament synthetic yarn having variable properties along its length comprising applying to the spun, solidified, undrawn yarn a plasticiser for the yarn material in an amount varying along the length of the yarn to produce relatively plasticised yarn portions and relatively unplasticised yarn portions and thereafter drawing the yarn to an extent such that variable properties are imparted along its length.

2. A process as in claim 1 wherein the yarn is continuously forwarded from a spinneret through a zone where the plasticiser is applied thereto and is immediately and continuously forwarded to the drawing operation and wheren said drawing operation draws the yarn an amount at least sufficient to impart thickness variations along its length in accordance with the variations in the prior application of the plasticiser.

3. A process as in claim 1 including winding up the yarn between the step of applying the plasticiser and the drawing step.

4. A process as in claim 1 wherein the yarn is drawn below its natural draw ratio.

5. A process as in claim 1 including continuously forwarding the yarn through a zone where the plasticiser is applied by contacting the yarn with a source of the plasticiser and wherein the contacting step includes moving the yarn to vary the contact of the yarn with the source to thereby eifect the variations of plasticiser along the length of the yarn.

6. A process as in claim 5 including the steps of generating signals and moving said yarn path in accordance with said signals.

7. A process as in claim 6 wherein the signals are generated according to pusedo-random pattern.

8. A process as in claim 1 wherein the plasticiser is initially applied unformly along the length of the yarn and is thereafter rendered non-uniform.

References Cited UNITED STATES PATENTS 2,953,427 9/1960 Egger 264-167 2,975,474 3/1961 Smith 264-167X 3,185,613 5/1965 Adams 264-167X 3,234,596 2/1966 Sims 264167X 3,263,298 8/1966 Holton 264167X 3,275,732 9/1966 Macleod et al. 264-167X 3,284,871 11/1966 Yano et a1. 264-167X 3,302,385 2/1967 Ruddell et a] 264-168X 3,323,165 6/1967 Mottern et a1. 264167UX 3,358,344 12/1967 Daniel 264-168X 2,034,008 3/1936 Taylor 264-131X 2,862,284 12/1958 Wicker 260-37WPUX 3,102,323 9/1963 Adams 8130.1X 3,394,429 7/1968 Nakagawa et a1. 264167X 3,415,918 12/1968 Holton et al. 264290X JAY H. WOO, Primary Examiner US. Cl. X.R. 171-7; 264290 

